Fix text alignment ribbon commands

[code-by-sia]

Summary

• Fixes the Format ribbon alignment buttons to send the string values expected by the core align command.
• Keeps active alignment state based on the existing TextAlign enum.
• Adds regression coverage for center/right alignment command payloads.
• Regenerates GitHub Pages build assets.

Verification

• npm test
• npm run typecheck
• npm run build
• npm run build-storybook

Notes:

• npm run build still reports the existing direct eval warning in src/lib/core/formula/Evaluator.ts; build succeeds.
• npm run build-storybook reports large Storybook bundle chunks; the static Storybook build succeeds.